diff --git a/examples/sim.sial b/examples/sim.sial
index 1ee9359..10155f2 100644
--- a/examples/sim.sial
+++ b/examples/sim.sial
@@ -1,4 +1,16 @@
-fun foo x = x
+// start
+
+fun foo x = do
+    69 // unused
+    print("Hi")
+    x
+end
+
+/* block comment
+
+fun invalid =
+
+*/
 
 fun fac n = if n == 0 then 1 else n * fac(n - 1)
 
@@ -6,3 +18,5 @@ fun main = do
     print(foo(1))
     print(fac(5))
 end
+
+// end
\ No newline at end of file
diff --git a/parser/src/lib.rs b/parser/src/lib.rs
index 54126c6..f69128c 100644
--- a/parser/src/lib.rs
+++ b/parser/src/lib.rs
@@ -174,15 +174,25 @@ pub fn lexer() -> impl Parser<char, Vec<(Token, Span)>, Error = Simple<char>> {
         .or(symbol)
         .or(delim)
         .or(keyword)
+        .map_with_span(move |token, span| (token, span))
+        .padded()
         .recover_with(skip_then_retry_until([]));
 
-    let comment = just("--").then(take_until(just('\n'))).padded();
+    let comments = just('/')
+        .then_ignore(
+            just('*')
+                .ignore_then(take_until(just("*/")).ignored())
+                .or(just('/').ignore_then(none_of('\n').ignored().repeated().ignored())),
+        )
+        .padded()
+        .ignored()
+        .repeated();
 
     token
-        .padded_by(comment.repeated())
-        .map_with_span(|token, span| (token, span))
-        .padded()
+        .padded_by(comments)
         .repeated()
+        .padded()
+        .then_ignore(end())
 }
 
 pub fn lex(src: String) -> (Option<Vec<(Token, Span)>>, Vec<Simple<char>>) {